From the past, liquid crystal display devices and organic electroluminescent (EL) panels have been used as display means of various types, such as monitors for televisions or PC monitors, displays for portable telephones or smartphones, displays for portable type game machines, displays for tablet terminals or wearable terminals, or displays for use in vehicles or the like. In recent years, in display devices of this type, from the standpoint of providing finer pitch, reducing weight, and enhancing thinness, various manufacturing methods have been employed. In such manufacturing methods, drive ICs are mounted directly on a glass board of a display panel, or a flexible board on which drive circuitry or the like is formed is mounted directly on a transparent board, such as a glass board, of a display panel with the use of anisotropic electrically conductive film (ACF).
A plurality of transparent electrodes made from indium tin oxide (ITO) or the like are formed on a glass board to which ICs or a flexible board are to be mounted. Electronic components such as ICs or a flexible board are connected to these transparent electrodes. In such electronic components that are to be connected to the glass board, a plurality of electrode terminals (bumps) corresponding to the transparent electrodes are formed on their mounting surfaces. The electronic components are thermocompression-bonded to the glass board interposed by an anisotropic electrically conductive film. Thus, the electrode terminals and the transparent electrodes are connected to each other.
An anisotropic electrically conductive film is made by mixing electrically conductive particles into a binder resin and shaping the result into a film. The anisotropic electrically conductive film is thermocompression-bonded between two electrical conductors, thereby providing electrical continuity between two electrical conductors and maintaining mechanical connection between two electrical conductors via the binder resin. A thermosetting binder resin having high reliability is commonly employed as the adhesive incorporated in such an anisotropic electrically conductive film. A photocurable binder resin or a photo-thermal dual curing type binder resin may also be employed as the adhesive.
When an electronic component is connected to a transparent electrode interposed by such an anisotropic electrically conductive film, first, the anisotropic electrically conductive film is provisionally adhered to the transparent electrode of the glass board with a provisional pressure bonding means (not illustrated). And, next, after a temporary connection body has been formed by mounting the electronic component on the glass board interposed by the anisotropic electrically conductive film, the electronic component is heated and pressed toward the transparent electrode along with the anisotropic electrically conductive film by a thermocompression bonding means such as a thermocompression bonding head or the like. By applying heat with this thermocompression bonding head, the anisotropic electrically conductive film undergoes a thermal hardening reaction, and due to this the electronic component is adhered to the transparent electrode.